首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8146篇
  免费   305篇
  2020年   98篇
  2019年   162篇
  2018年   195篇
  2017年   203篇
  2016年   236篇
  2015年   172篇
  2014年   167篇
  2013年   2408篇
  2012年   244篇
  2011年   257篇
  2010年   282篇
  2009年   239篇
  2008年   177篇
  2007年   204篇
  2006年   190篇
  2005年   122篇
  2004年   98篇
  2003年   104篇
  2002年   113篇
  2001年   131篇
  2000年   108篇
  1999年   132篇
  1998年   108篇
  1997年   84篇
  1996年   86篇
  1995年   83篇
  1994年   77篇
  1993年   80篇
  1992年   63篇
  1991年   67篇
  1990年   59篇
  1989年   76篇
  1988年   63篇
  1987年   84篇
  1986年   73篇
  1985年   85篇
  1984年   93篇
  1983年   85篇
  1982年   66篇
  1981年   84篇
  1980年   88篇
  1979年   81篇
  1978年   61篇
  1977年   81篇
  1976年   59篇
  1975年   60篇
  1974年   48篇
  1973年   45篇
  1972年   51篇
  1970年   48篇
排序方式: 共有8451条查询结果,搜索用时 15 毫秒
131.
A major part of the ethnographic literature concerning present-day Irian Jay a is based on research dating back to the 1950s and 1960s. Following the independence of Indonesia, West New Guinea remained a separate Dutch colony between 1950 and 1962. The Dutch colonial administration had had little ethnographic interest in the area since the beginning of the century, so that interest in knowledge concerning the indigenous population had yet to develop. Lack of manpower, finances and time to instigate adequate research meant that the resulting search for ethnographic data became itself a complex social process. People from a range of backgrounds and training - not only academic researchers, but also administrative and missionary personnel - became involved in the gathering of ethnographic material, often while engaged in quite different duties. In this article some light is shed both on the resulting structure of research and on the motivations behind the separate research efforts. At the end of the article some conclusions are drawn concerning the nature of the material gathered.  相似文献   
132.
133.
134.
135.
136.
137.
While research has tackled the hub-and-spoke network design problem, that research has overlooked the air-truck modal integration issue which is a common feature of real express delivery systems. This paper devises integer linear programs to represent the mode and route assignment aspects of the operational problem. The model is solved under four different levels of delivery schedule, and the results show that as the promised delivery schedule is relaxed, not only does the use of truck routes become more desirable, but also interesting adjustments in mode and hub assignment occur. Consider the case of hubs in Los Angeles and Dayton. As the time constraints are relaxed, cities such as Minneapolis and New Orleans originally linked by air to Los Angeles, switch to Dayton because cheaper truck routes become feasible.  相似文献   
138.
139.
140.
By 1980, the Brasilian steel industry had grown to be the eighth largest among the market economies. It is a largely state-owned industry, much of the expansion of which has been funded by international capital. The pattern of development has not been externally imposed, however, but rather reflects the changing balance of class forces within Brasil as policies oscillate between nationalist, populist limits on foreign investment and open, pro-development strategies that rely on foreign investment. Both policies develop their own contradictions, that are reflected in frequent military interventions.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号